1. Field of the Invention
The present invention relates to vibration damper for disk devices such as optical disk devices and magneto-optical disk devices which are used for acoustic equipment, video equipment, information equipment, various kinds of precision equipment, and the like regardless of whether they are mounted on vehicles or designed for consumer products. In particular, the present invention relates to a viscous fluid-filled damper for damping vibrations of a supported body such as a mechanical chassis which is composed of a motor, an optical pickup, a disk table, and the like, and to a mounting structure of the viscous fluid-filled damper.
2. Description of the Related Art
As shown in FIG. 20 as an example, a disk device 1 is structured such that a disk 2 for recording and playback, such as an optical disk or a magneto-optical disk in a format of a CD or a CD-ROM, is horizontally chucked on a disk table 3, that the disk 2 is rotated integrally with the disk table 3, which is rotated by a motor, at a high speed, and that an optical pickup 4 approaches the disk 2 and tracks it in a radial direction of the disk 2 to record data thereon and play back the contents thereof. A coil spring 7 joins a mechanical chassis 5 to a box body 6 of the disk device 1, and a viscous fluid-filled damper 8 is interposed between the mechanical chassis 5 and the box body 6, so the disk device 1 blocks off or damps vibrations transmitted from the outside.
As shown in FIG. 21, the viscous fluid-filled damper 8 is obtained by sealing a viscous fluid 13 such as silicone oil in a sealed container. The sealed container is formed of a lid portion 9 made of a hard resin, a peripheral wall portion 10 made of a hard resin and rising vertically from the lid portion 9, a flexible portion 11 made of a thin rubber-like elastic material assuming a shape of bellows, and a stirring recess portion 12 protruding into the damper. The viscous fluid-filled damper 8 is mounted as follows. That is, while a screw 9b is inserted into a screw hole 9a provided through the lid portion 9 so as to fasten the viscous fluid-filled damper 8 on the box body 6, a stirring shaft 14 provided on the mechanical chassis 5 is inserted into the stirring recess portion 12 so as to couple the viscous fluid-filled damper 8 to the mechanical chassis 5.
In the viscous fluid-filled damper 8 according to this conventional example, the stirring recess portion 12 is formed of a rubber-like elastic material such as thermoplastic elastomer, which exhibits high flexibility. Therefore, workability in inserting the stirring shaft 14 into the stirring recess portion 12 is not good, and the stirring shaft 14 cannot be appropriately inserted into the stirring recess portion 12 in some cases. If the mechanical chassis 5 or the box body 6 is exposed to strong vibrations or a strong impact, the stirring shaft 14 may slide along an inner wall face 12a of the stirring recess portion 12 to cause an incomplete state of insertion or cause a deterioration in vibration damping function even when the stirring shaft 14 is inserted correctly. If the stirring shaft 14 has not been inserted correctly, such inconveniences become more likely to occur. Accordingly, the stirring shaft 14 is required at least to have been inserted into the stirring recess portion 12 correctly.
To confirm whether or not the stirring shaft 14 has been appropriately inserted into the stirring recess portion 12, there is a method in which the stirring recess portion 12 is pressed against the lid portion 9 to make a judgment depending on whether or not a tip of the stirring recess portion 12 bends. In this method, however, since the stirring recess portion 12 is pressed against the lid portion 9, the thin flexible portion 11 may be excessively extended and damaged.
To replace this method, there is known a viscous fluid-filled damper having a structure in which the stirring recess portion 12 and at least one of the peripheral wall portion 10 and the lid portion 9 are translucent as disclosed in, for example, JP 2001-57068 A. This viscous fluid-filled damper makes it possible to visually determine with ease whether or not the stirring shaft 14 has been inserted into the stirring recess portion 12 correctly, despite the structure in which the stirring shaft 14 is hidden inside the stirring recess portion 12.
However, the viscous fluid 13 that fills the damper is color-coded to distinguish between grades of merchandise or the like in some cases, even when the viscous fluid-filled damper disclosed in JP 2001-57068 A is used. In the case where the colored viscous fluid 13 is used, the state of insertion cannot be confirmed even when the stirring recess portion 12, the flexible portion 11, and the like are made translucent.
Moreover, in order to visually confirm an internal state, the translucency of the flexible portion 11 and the stirring recess portion 12 needs to be close to transparency. Therefore, a range of material selection is narrowed, and a rise in cost may be caused in some cases.